81747431 has 2 divisors, whose sum is σ = 81747432. Its totient is φ = 81747430.

The previous prime is 81747397. The next prime is 81747439. The reversal of 81747431 is 13474718.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81747431 - 2¹⁰ = 81746407 is a prime.

It is a super-2 number, since 2×81747431² = 13365284950199522, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 81747391 and 81747400.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81747439) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40873715 + 40873716.

It is an arithmetic number, because the mean of its divisors is an integer number (40873716).

Almost surely, 2^81747431 is an apocalyptic number.

81747431 is a deficient number, since it is larger than the sum of its proper divisors (1).

81747431 is an equidigital number, since it uses as much as digits as its factorization.

81747431 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18816, while the sum is 35.

The square root of 81747431 is about 9041.4285928718. The cubic root of 81747431 is about 434.0016405043.

The spelling of 81747431 in words is "eighty-one million, seven hundred forty-seven thousand, four hundred thirty-one".